DESCRIPTION: The investigators propose to examine the cohort of women and their offspring who were exposed to polybrominated biphenyls (PBB) as a contaminant in cattle feed in 1973. The Michigan Department of Health has followed this cohort for more than 20 years. These investigators propose to ascertain the occurrence of a number of health outcomes in the women and their offspring in order to determine if there is evidence of endocrine disruption associated with PBB exposure. A telephone interview will be administered to approximately 1900 women currently in the cohort to ascertain the cumulative incidence since exposure of endocrine sensitive endpoints, such as endometriosis, benign breast disease, abnormal Pap smears, fibroids, and thyroid dysfunction. Among appropriate subgroups of the cohort, they will ascertain the cumulative incidence of infertility, time to pregnancy, duration of lactation, rates of spontaneous abortion and stillbirth, menstrual cycle characteristics, age at menopause, and cumulative incidence of hip fracture. In the female offspring of exposed women, determinations will be made of age at menarche and menstrual cycle characteristics. Medical records will be reviewed to verify each of the clinical conditions. The occurrence of these outcomes will be modeled by multivariate methods as a function of PBB serum level in 1976, controlling for potentially confounding variables.